Method of and apparatus for making propellers



AORNEY L. T-. FREDERICK Filed May 15, 1919 Louis T Frederic/r METHOD OF AND APPARATUS FOR MAKING PROPELLERS Apr. 10, 1923 WITNESSES:

LOUIS '1. FREDERICK, OF WILKINSBURG, HOUSE ELECTRIC & MANUFACTURING VANIA.

- .METHOD OF AND APPARATUS FOR MAKING PROPELLERS.

, Application fi l egjl may 15,

T 0 all 'tvhom concem Be it known that- I, Doors T. FREDEriICK, a citizen-of the United States, and; a resident of Wilkinsburgi in; the county of Allegheny a State Q nnsylana', a eiavented ,Electric and Manufacturing Co., are disclosed propellersformed of superimposed sheets of fibrous. material, such paper, duck and the, like, impregnatedwith 'a binder such as a phenolic condensation prod not w ichis hardened b the application of heat andpr essurej hese applications also disclose the curing of ro'pellers'of this character in a mold in which they are sub jected to the simultaneous-actionof heat and pressure until the binder has been transformed to its final. solid and substantially infusible and insoluble state. i i I have found, however, that, while reasonable satisfaction is obtained by following the methods set forth in -theseapplications, it is very difficult to. obtain absolute accuracy ofthe bladeangles so that all propellers curedin a single mold may not be identical and, in some instances. the angle of oneblade may vary slightly from that of the other.

Furthermore, it is sometimes desirable to mold propellers in which the blade angles of one will vary slightly fromthose of another and, with a single mold, this is impossible w-hen the propellers are cured in the manner disclosed in the abo've-referred-to ap li'cati ons. I v f I 11 view of these facts, one of the primary objects of my present invention resides in providing a method of curing propellers such as to insure-absolute uniformity of the blade angles and such that, if desired, the blade angles of various propellers may be slightly varied at will.

A still further object of my invention revlik pa supporting 1,451,541 Pr ce.

PENNSYLVANIA, ASSIGNOR TO WESTING- COMPANY, A CORPORATION OF PENNSYL- 1919. Serial No. 297,352.

sides in the provision of an apparatus for 'these and other objects in view, my

tioii'will be more fully described, illustrated inthe drawings, in the several views practising my invention. which shall be ecoj'n'om cal and slmple in construction and con-, \jenientin use.

of "which corresponding numerals indicate 'ts."a nd then particularly pointed out "in the claims.

I Fig. 1 is a plan view of an apparatus suitable fonpractising my invention, showing a propellerlin place, and Fig. 2 is a side elevation of the structure shown in Fig. 1.

[have found that, if a propellerbody formed of superimposed layers of fibrous sheet material and. a binder which hardens under the application of heat and pressure, such as a phenolic condensation product, is subjected to heat and pressure in a mold, in the manner disclosed in the previously-referred-to applications, for a relatively short time,i the binder will be nearly, but not en-' tirely, hardened, the outer portion of the body being fully hardened and the inner portion being only partly cured. If the pro p'eller is then removed from the mold and clamped in such manner as to bring the thrust-faces of its blades at the proper angles and'is then baked for a relatively long period of time, until the curing is completed, the blades will become permanently set at the exact angles at which they were clamped.-

My present invention resides in the discovery of this process and in the provision of a suitable apparatus for carrying it out.

In thedraivings, I have illustrated one form ofapparatus suitable for the purpose which may comprise a base 1, of any suitable material, preferably metal, provided cured propeller 5, of the character previously specified. The space at each side of the center st is provided with spaced rackets 6, the upper facesv of which are preferably inclined at the angles desired for the propeller blades, it, of course, beingunderstood that the inclination of theupper faces of the brackets at one side is the reverse of the inclination of the upper faces of the brackets at the other side.

Clamp plates 7 are supported upon the inclined facesof the brackets to receive the indicated in the drawings; and additional clamp plates 8 are disposed upon the back faces of the propeller blades,,bein preferably. curved, to roughly ,corr, pon 1. to the, aw y k a ,r. L is .1 i Brace strips 9 vof metal may: heypositipned curvature of the blades.

upon, or secured to, the edge portions of the upper clamping plates 8, and' icla-mping bands 10 are disposed transversely of the upper clampin tended througi brackets to draw the thrust'faces of the blades into position againstf 'the lower clamp plates. f

In practising my "invention with the above-described apparatus,- l may assemble a propellerbody as set forth in either of the applications referred to and partly cure it,

at a relatively high temperature, in a mold,

under pressure. A temperature of approximately 180 C. may be satisfactorily employed during the moldingoperation and the molding may be continued from two to four hours, more or less, dependent upon the materials employed and the size ofthe propeller. The propeller,- in its nearly but not completely cured stateQma y then be removed from the mold and clamped-mp0s tion upon the reforming mold or support above described, as clearly shown in Figs. 1 and 2 of the drawings. When '50 clamped; the curing of the prop'ellermay be com plet'ed'byhakingit at a relatively. low ternperature of from 100 110125 0; fora suit able length of time, as from four: to twelve "hours. This baking may be done man tom'a v j a mol ,inthat'it greatly shortens" the length 7 form ofoven'suitable for the pur'pose fland may be continued for a time'varyin j cordance with'the size of 'thepropel e A propeller thus pre-cu'red in a- -mold and subsequently bakedwill have its blades permanently set at the angles to which they are clamped so that absoluteunifo'rmity in blade angles is insured. Obviously,;by interposing wedges orshims "between 'the upper faces of the brackets and the lower clamping plate, the blade angles may be slightly altered, during baking; from the angles initially given'the'm by the preliminary treatment in the mold. 1

Besides the advantages labove referred to, the present method is preferablef tothe cusmethod offully curing propellersin of time during which the relatively expen' sive' mold and. press are employed": thereby greatly reducing jthe cost of f Quantity pro- 1 plates. -Bolts 11 araeX- openings formed in the@ clamping bands and are-screwed 'into 'the apparatus, employed in practising it, may

be resorted. and I, therefore, reserve the rightggtosmake any changes in either, which 1 shall fall within the scope of the claims.

I claim as 1. Then formed; binder iwliic'h; comprises subjecting the propeller'togheat, and pressure inamold to pars my invention tiallyi-chre'zand harden the binder, clamping the propeller with :the thrust faces of its bladesia'tithe desired angles and baking the propellersmto complete the curing and hardening of the; binder.

2. fllheiitrmethod of curing a propeller formed of'fibrous sheet material and a phenolic condensation product as a binder which comprises partly curing the propeller by subjecting it to relatively high heat and pressure in a mold, removing the propeller' from themold, clamping the propeller to a suppoirtiavith i't'sithrust faces held at the desiredJang-les'; P'and baking the propeller at a relatively loiv temperature untih the binder iscompletelyhardened; U a :3; iAn-mpparatus for use in, curing propellers? comprising a base, hub-engaging means c airied: thereby, supporting elements haiz-ingl portions inclined ;a,t. the desired an- ,lalBStfOl'dlil lB thrust faces ofthe' blades, and nieansfo l mping; the blades against such portions =1. zAaaAn apparatus-for, use. in curing pro pellers which-[comprisessupports for the pif opiellenbladesdisposed at the desiredangles to receive the thrust faces of the blades, means;forcclampingthe blades against the supports, and hub-engaging means for securing the hub-in proper relation to the blades. i T I g 55 An apparatus for use in molding propellers whiclrcomprises a base, a hub-engaging meanscarried thereby, supports carried by the ibase and having inclined portions td receive the thrust faces of pro peller bladesyclamping plates for engage me'nt against the thrust and back faces of the blades against the supports and between t-he:'clampi'ng.plates. I 3

wIn testimony whereof, ;I have hereunto subscribed my name this 30th dayv of April,

10;:- ethodgof curing a propeller :9 zifibroust sheet material and a 

